Fire-resisting glass

ABSTRACT

There is provided a fire-resisting glass including a first laminated glass pane made of two float-glass panes connected via an intermediate organic layer, a second laminated glass pane made of two float-glass panes connected via an intermediate organic layer, an airtight clearance between the two laminated glass panes which is evacuated or filled with a gas, wherein a thermal insulation layer is provided on at least one of the sides of the float-glass panes facing the intermediate organic layer or the clearance. The thermal insulation layer may be provided on the two sides of the laminated glass panes facing the clearance.

This application is the US national phase of international applicationPCT/EP02/12345 filed in English on 5 Nov. 2002, which designated the US.PCT/EP02/12345 claims priority to DE Application No. 101 55 273.4 filed9 Nov. 2001. The entire contents of these applications are incorporatedherein by reference.

1. TECHNICAL FIELD

The present invention relates to a fire-resisting glass. Fire-resistingglasses are classified in accordance with their behavior under fireconditions: in the fire test as per DIN 4102, fire-resisting glasses ofthe fire-resistance classes F (so-called F-glazing) have to securelyprevent flames and smoke from extending as well as heat radiation frompenetrating. Fire-resisting glasses of the fire-protection classes G(G-glazing) merely have to prevent flames and smoke from extending. Thepenetration of heat radiation is only to be impaired. The duration inminutes for which a fire-resisting glass fulfills these requirements inthe event of a fire determines its fire-protection class (e.g. G30, G60,F30, F60 etc.). In the description of the present invention the termfire-resisting glass is exclusively used for glasses fulfilling at leastthe requirements of one fire-protection class.

2. PRIOR ART

Various concepts for the construction of a fire-resisting glass areknown from the prior art. For example, wired glasses are used wherein awire braid reinforcement is incorporated into the glass. Another conceptare sandwich constructions made of two or more panes of common floatglass wherein one or more gel-like inter-mediate layers are provided,typically made of a water-containing alkali silicate. These intermediatelayers foam with increasing temperature and become opaque. Together withthe float glass panes, already cracked due to the heat, thiscomparatively strong foam can maintain its room-closing effect in thecase of a fire. An example for such a fire-resisting glass with a totalof three panes is disclosed in DE 199 16 506.

In order to improve the mechanical properties of such a fire-resistingglass, it is moreover known to use laminated glass panes instead ofsimple float glass panes enclosing the fire-hindering alkali silicatelayer, wherein each of these panes consists of two float-glass panes,connected by means of a plastic foil.

Another concept is disclosed in the EP 1 088 651. Here, a resin layer isprovided between the two glass panes, darkening when the temperatureincreases, and thus preventing heat radiation from penetrating.Moreover, an IR reflection layer is provided on at least one of the twoglass panes.

Another fire-resisting glass is known from GB 2 289 496. A ceramic glasspane with a very high melting point is provided between two common floatglass panes in order to achieve the necessary mechanical stability.

Finally, it is known to improve the endurance of glasses under fireconditions by means of using special materials, e.g. boron silicates,for the glass instead of the common float glass made of soda-lime silicaglass; these materials have lower thermal coefficients of expansion andhigher melting points. Alternatively, the glass is pre-stressed in orderto achieve a higher breaking resistance. A fire-resisting glass of thistype is for example disclosed in EP 0 608 457.

All mentioned fire-resisting glasses from prior art have, however, thedisadvantage of substantially higher production costs than panes madeout of common float glass. Moreover, they can only be processed withhigher expense, thus increasing the cost for production of windows ordoors made of these glasses. This is particularly true for pre-stressedglasses. Moreover, the mechanical properties of many fire-resistingglasses, e.g. binding of splinters and the capability not to collapseeven if cracks are present are as bad as the thermal insulatingproperties. Therefore, the present invention is based on the problem toprovide a low-cost fire-resisting glass, combining good mechanical andthermal properties and low production cost.

3. SUMMARY OF THE INVENTION

With regard to a first aspect, the present invention relates to afire-resisting glass with a first laminated glass pane made of two floatglass panes connected by means of an intermediate organic layer, asecond laminated glass pane made of two float-glass panes connected bymeans of an intermediate organic layer, an airtight clearance betweenthe two laminated panes, which is evacuated or filled with a gas,wherein a thermal insulation layer is provided on at least one of thefloat-glass pane's sides facing the intermediate organic layer or theclearance. Preferably, the thermal insulating layer is provided on bothsides of the laminated glass panes, facing the clearance.

The invention is based on the surprising realization that thecombination of a known insulating glass made of two laminated glasspanes having alone not sufficient fire-resisting properties with athermal insulation layer being sufficiently effective also at hightemperatures leads to a glass which can be used as fire-resisting glass,since it at least fulfills the requirements of low fire-protectionclasses. In the fire test, the endurance amounted to clearly more than30 minutes. Contrary to the fire-resisting glasses of the prior artexplained above, such a glass can be produced and processed atconsiderably lower cost. Moreover, the fire-resisting glass as per theinvention has clearly better mechanical and thermal properties.

According to a further aspect of the present invention, the presentinvention relates to a fire-resisting glass with a first and a secondfloat-glass pane, wherein the first and the second float-glass paneadhere to an intermediate organic layer provided between them, wherein athermal insulating layer is provided on the side of the first and/or thesecond float-glass pane facing the intermediate organic layer, andwherein a pyrolitic layer is provided on the side of the first and/orsecond float-glass pane opposite the intermediate organic layer.

Thus, even a known laminated glass pane can be used as fire-resistingglass within the meaning of the above definition as long as the thermalinsulation properties are sufficiently improved by the two mentionedlayers.

The pyrolitic layer preferably comprises fluorine (F) doped tin oxide(SnO₂) while the thermal insulating layer is preferably a silver (Ag)based layer with an emissivity of <0.1, in particular 0.04. A thermalinsulating layer comprising a series of layers SnO₂, Ag, SnO₂, SiN,starting from the glass surface, is particularly preferred.

Further improvements of the fire-resisting glasses as per the inventionare the subject matter of further dependent claims.

4. BRIEF DESCRIPTION OF THE DRAWINGS

Presently preferred embodiments are described in the following detaileddescription, referring to the drawings and showing:

FIG. 1: a section through a fire-resisting glass according to a firstembodiment of the present invention;

FIG. 2: a section through a fire-resisting glass according to a secondembodiment of the present invention;

FIG. 3: a schematic view of the stack of a preferred thermal insulationlayer for the fire-resisting glasses as per FIGS. 1 and 2.

5. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a first preferred embodiment of the present invention in aschematically simplified vertical section through a fire-resisting glass10. The thicknesses of the individual panes 20, the intermediate organiclayers 30, or layers 50 are not to scale. This is also true for thesubsequent FIGS. 2 and 3.

As can be perceived, two laminated glass panes are provided at the rightand left hand side of a clearance 40, each of them comprising glasspanes 20 connected by means of an intermediate organic layer provided asa foil 30. The panes 20 are non-treated float-glass, i.e. float glass,which can be produced at low-cost and out of soda-lime silica glass inthe float method.

The foil 30 is made of a thin plastic materials—as common with laminatedglass—, for example of a plasticized polymer based on polyvinylbutyral,and assures that splinters of the panes 20 are bound and that thecapability of a splintered pane not to collapse is increased. Besidesplastic materials based on PVB, other materials can be used for thefire-resisting glass, in particular if they have higher thermalresistance (e.g. EVA, cast resins, teflon).

The clearance 40 between the two laminated glass panes is defined byspacing elements 60, either made of heat-resistant plastic materials orof metals. Typical dimensions of the fire-resisting glass as per theinvention are four glass panes 20 of 4 mm thickness, two PVB foils 30 of0.76 mm thickness, and a clearance 40 of 16 mm thickness. Although FIG.1 shows a fire-resisting glass consisting of only two laminated glasspanes, it is also possible to provide more than two laminated glasspanes with a corresponding plurality of clearances 40, for example ifthe requirements of higher fire-protection classes are to be fulfilled.

In order to avoid condensation of air moisture or even corrosion of thethermal insulation layers 50 described below, the clearance 40 isevacuated or filled with a gas such as argon. The seals for theclearance 40 (not shown in FIG. 1) are preferably made of aheat-resistant silicone. On the whole, a fire-resisting glass 10 is thusprovided at low costs, having good usage properties in addition to fireprotection. For example, the sound insulation of the describedconstruction amounts to approx. 42 dB and is thus clearly above thevalues for known fire-resisting glasses.

The four glass panes 20 of the exemplary fire-resisting glass 10 shownin FIG. 1 have a total of eight surfaces 1-8. A thermal insulating layer50 with a very low emissivity is preferably provided on the surfaces 4and 5. Preferred values are below 0.1. An emissivity under 0.04 isparticularly preferred. The thermal insulation layer of this emissivityis based on a silver layer surrounded by dielectric materials.

The preferred stack of the thermal insulation layer is schematicallyshown in FIG. 3: A SnO₂ layer of approx. 35 nm thickness is provideddirectly on the float-glass pane 20. Approx. 4 nm ZnO are provided ontop of it, followed by an Ag layer of approx. 12 nm thickness. Anintermediate NiCrO_(x), (x=0 . . . 2) layer of approx. 1 nm thickness isfollowed by a further SnO₂ layer of about 30 nm. This preferred stack isconcluded by a SiN layer of about 20 nm thickness. SiN can alternativelybe used instead of the upper SnO₂ layer.

The layers described are preferably deposited on the float-glass panesby means of a PVD method (physical vapor deposition), such as sputterdeposition.

Surprisingly, the fire test as per DIN 4102 showed for theabove-explained fire-resisting glass that this construction, i.e. alaminated insulating glass with thermal insulation layer without aspecial layer of water-containing alkali silicate or the like, andwithout using special pre-stressed glasses, fulfills at least therequirements of the fire-protection class G 30. The followingobservations have been made:

At first, the outer pane 20, facing the fire, breaks. Due to itscapacity not to collapse even in the broken state, the outer laminatedglass pane, however, does not fall apart for the time being. Thus, boththermal protection layers 50 can prevent excessive heating of the innerlaminated glass pane during this period. Therefore, temperatures ofmerely 40° C. are measured on the outer surface of the laminated glasspane opposite to the fire during the initial phase of the fire test. Thesecond laminated glass pane does not show damages until after 18 min.before it finally collapses after clearly more than 30 minutes so thatflames and smoke can penetrate.

Additional thermal insulation layers on the surfaces 1, 2, 3, 6, 7, 8 ofthe panes 20 can further increase the endurance of the fire-resistingglass 10 in the discussed fire test. A pyrolitic layer made of doped tinoxide (SnO₂) is preferably used for the surfaces 1 and 8 facing theoutside, preferably deposited on the corresponding float-glass pane 20by means of a CVD process (Chemical vapor deposition).

FIG. 2 shows an even simpler construction of a fire-resisting glass 10′,which can also fulfill the requirements of the lowest fire-protectionclass G 30. Here, a known laminated glass made of two panes 20 and aconnecting plastic foil 30 is modified by means of one or more thermalinsulation layers 50 on the sides 2 and 3, facing the foil. Endurance ofthe second float-glass pane 20 is significantly increased in thisembodiment by means of the large radiation shielding of the thermalinsulation layers 50. For this embodiment, too, the preferredcomposition of the thermal insulation layer 50 is the stack shown inFIG. 3.

Additionally, a pyrolitic layer 70 is provided on the side facing thefire in order to postpone premature heating of the foil 30 and of thepane 20, opposing the fire. Such a pyrolitic layer 70 can also beprovided on the other outer surface 4, if the fire-resisting glass isused symmetrically, expecting fire from both sides.

1. Fire-resisting glass fulfilling at least the requirements offire-protection class G30 and consisting essentially of: a. a firstlaminated glass pane comprising two float-glass panes connected by meansof an intermediate organic layer; b. a second laminated glass pane ofthe fire-resisting glass comprising two float-glass panes connected bymeans of an intermediate organic layer; c. an airtight clearance betweenthe two laminated glass panes being evacuated and/or filled with a gas,and d. a thermal insulation layer comprising an infrared (IR) reflectingmetal layer is provided on at least one of the sides of the float-glasspanes, facing the intermediate organic layers, and wherein thefire-resistant glass fulfills at least the requirements offire-protection class G30.
 2. Fire-resisting glass in accordance withclaim 1, wherein a pyrolitic layer is additionally provided on at leastone of the sides of the first and/or second laminated glass-pane, facingtowards the outside.
 3. Fire-resisting glass in accordance with claim 2,wherein the pyrolitic layer contains fluorine doped tin oxide. 4.Fire-resisting glass in accordance with claim 1, wherein the thermalinsulation layer is a layer based on silver, having an emissivity of<0.1.
 5. Fire-resisting glass in accordance with claim 4, wherein thethermal insulation layer comprises a series of layers SnO₂ Ag, SnO₂,SiN, seen from the glass surface.
 6. Fire-resisting glass in accordancewith claim 4, wherein the thermal insulation layer comprises respectivelayers comprising, from the glass substrate outwardly, tin oxide,silver, silicon nitride, silicon nitride.
 7. Fire-resisting glass inaccordance with claim 4 wherein a ZnO layer is additionally providedbelow the silver layer, and wherein a NiCrO_(x) layer is provided on topof the silver layer.
 8. Fire-resisting glass in accordance with claim 1,wherein the thermal insulation layer comprises the following layers,from the glass surface outwardly: 35 nm SnO₂, 4 nm ZnO, 12 nm Ag, 1 nmNiCrO_(x), 30 nm SnO₂ 20 nm SiN.
 9. Fire-resisting glass in accordancewith claim 1, wherein the thermal insulation layer is a layer based onsilver, having an emissivity of <0.04.
 10. Fire-resisting glass inaccordance with claim 1, wherein the thermal insulation layer is a low-Ecoating comprising a layer comprising silver.